A router is a networking device that forwards data packets between computer networks. The router may include Local Area Network (LAN) ports, Wide Area Network (WAN) ports, and Universal Serial Bus (USB) interfaces. The WAN port can be connected to an outside networks, for example, an Asymmetric Digital Subscriber Line (ADSL) telephone line or wireless telecommunication networks. The LAN port can be connected to an Ethernet switch or a personal computer, and the USB interface can be connected to wireless data cards. When the WAN port is switched from a network to another network, Internet Protocol (IP) address of the WAN port can be changed too, and IP address of the LAN port needs to be updated accordingly.